Most are also in extremely limited supply, the FDA said. Two U.S. Ebola patients, Dr. Kent Brantly and Nancy Writebol, are slowly recovering after receiving doses of one experimental medicine called Zmapp. Only a handful of doses of the drug have been manufactured so far, and prior to the patients receiving it Zmapp had only been tested in animals.

The virus is not a water-borne or food-borne illness and is not transmitted through the air, the FDA said. Ebola is only spread through direct contact with the body fluids of an infected person, or through needles and other items that have been contaminated with the virus.

According to the World Health Organization, the current outbreak of Ebola has killed 1,066 people in Guinea, Liberia, Nigeria and Sierra Leona, and sickened 2,000 more.